Detecting co-resident services in a container cloud

ABSTRACT

In an approach to detection of co-location of container services, a method may include receiving, by a first program in a first cloud container on a first host, a bit string over a side channel within a trial period of time. The method may also include determining whether a key corresponding to the bit string matches a pre-determined key corresponding to a second program in a second cloud container. The method may further include determining whether the second cloud container is located on the first host based, at least in part, on whether the key corresponding to the bit string matches the pre-determined key. The side channel may include a first resource on the first host that is accessible by cloud containers located on the first host and the bit string is received by monitoring the first resource for activity indicative of bit values.

BACKGROUND OF THE INVENTION

The present invention relates generally to the field of containers, andmore particularly to detecting co-location of services in a containerhost.

Containers are application delivery technology. They give developersflexibility to build and move applications without the need to rewriteor redeploy code. Containers provide tools to automate the deployment ofapplications. A container image is a stand-alone, executable package ofa piece of software that includes everything needed to run it includingcode, libraries, settings, and other necessary specifications.

SUMMARY

Embodiments of the present invention disclose a method, a computerprogram product, and a system for detecting co-resident services in acontainer host. The method may include receiving, by a first program ina first cloud container on a first host, a bit string over a sidechannel within a trial period of time. The method may also includedetermining whether a key corresponding to the bit string matches apre-determined key corresponding to a second program in a second cloudcontainer. The method may further include determining whether the secondcloud container is located on the first host based, at least in part, onwhether the key corresponding to the bit string matches thepre-determined key. The side channel includes a first resource on thefirst host that is accessible by cloud containers located on the firsthost and the bit string is received by monitoring the first resource foractivity indicative of bit values.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a cloud computing environment according to an embodimentof the present invention;

FIG. 2 depicts abstraction model layers according to an embodiment ofthe present invention;

FIG. 3 is a functional block diagram illustrating a distributed dataprocessing environment, in accordance with an embodiment of the presentinvention;

FIG. 4 is a flowchart depicting operational steps of a co-locationprogram for determining co-location of containers, in accordance with anembodiment of the present invention;

FIG. 5 is an illustration depicting an exemplary shared key, inaccordance with an embodiment of the present invention;

FIG. 6 is a graphic depiction of the transmission of a bit string over aside channel, in accordance with an embodiment of the present invention;and

FIG. 7 depicts a block diagram of components of the server computerexecuting the user identification program within the distributed dataprocessing environment of FIG. 3, in accordance with an embodiment ofthe present invention.

DETAILED DESCRIPTION

It can be difficult for two collaborative applications running ondifferent containers to find co-location (e.g., determine whether theyare running on the same host computer) without having direct access tothe host. In this context, a container is an isolated environment fromthe rest of a host system. Containers typically have limited access tomonitor the host system and virtually no access to monitor othercontainers running on the same host system. Containers run from asoftware image that provides all files necessary to execute a set ofprocesses, where the set of processes provide one or more services,e.g., web-based applications, databases, among others.

Embodiments of the present invention detect co-location of residentservices in a container cloud by encoding, by a first instance of aco-location program at a first container, a shared key K using an errorcorrection code (ECC) and successively transferring each bit b in bitstring s via one or more side channels c. A second instance of theco-location program at a second container receives a bit string s′ overthe one or more side channels c and determines key K′ by decoding bitstring s′ using the ECC. If the shared key K matches the determined keyK′, the second instance of co-location program determines that it ishosted on the same host computer as the first co-location program.

Implementation of embodiments of the present invention may take avariety of forms, and exemplary implementation details are discussedsubsequently with reference to the Figures.

It is to be understood that although this disclosure includes a detaileddescription on cloud computing, implementation of the teachings recitedherein are not limited to a cloud computing environment. Rather,embodiments of the present invention are capable of being implemented inconjunction with any other type of computing environment now known orlater developed.

Cloud computing is a model of service delivery for enabling convenient,on-demand network access to a shared pool of configurable computingresources (e.g., networks, network bandwidth, servers, processing,memory, storage, applications, virtual machines, and services) that canbe rapidly provisioned and released with minimal management effort orinteraction with a provider of the service. This cloud model may includeat least five characteristics, at least three service models, and atleast four deployment models.

Characteristics are as follows:

On-demand self-service: a cloud consumer can unilaterally provisioncomputing capabilities, such as server time and network storage, asneeded automatically without requiring human interaction with theservice's provider.

Broad network access: capabilities are available over a network andaccessed through standard mechanisms that promote use by heterogeneousthin or thick client platforms (e.g., mobile phones, laptops, and PDAs).

Resource pooling: the provider's computing resources are pooled to servemultiple consumers using a multi-tenant model, with different physicaland virtual resources dynamically assigned and reassigned according todemand. There is a sense of location independence in that the consumergenerally has no control or knowledge over the exact location of theprovided resources but may be able to specify location at a higher levelof abstraction (e.g., country, state, or datacenter).

Rapid elasticity: capabilities can be rapidly and elasticallyprovisioned, in some cases automatically, to quickly scale out andrapidly released to quickly scale in. To the consumer, the capabilitiesavailable for provisioning often appear to be unlimited and can bepurchased in any quantity at any time.

Measured service: cloud systems automatically control and optimizeresource use by leveraging a metering capability at some level ofabstraction appropriate to the type of service (e.g., storage,processing, bandwidth, and active user accounts). Resource usage can bemonitored, controlled, and reported, providing transparency for both theprovider and consumer of the utilized service.

Service Models are as follows:

Software as a Service (SaaS): the capability provided to the consumer isto use the provider's applications running on a cloud infrastructure.The applications are accessible from various client devices through athin client interface such as a web browser (e.g., web-based e-mail).The consumer does not manage or control the underlying cloudinfrastructure including network, servers, operating systems, storage,or even individual application capabilities, with the possible exceptionof limited user-specific application configuration settings.

Platform as a Service (PaaS): the capability provided to the consumer isto deploy onto the cloud infrastructure consumer-created or acquiredapplications created using programming languages and tools supported bythe provider. The consumer does not manage or control the underlyingcloud infrastructure including networks, servers, operating systems, orstorage, but has control over the deployed applications and possiblyapplication hosting environment configurations.

Infrastructure as a Service (IaaS): the capability provided to theconsumer is to provision processing, storage, networks, and otherfundamental computing resources where the consumer is able to deploy andrun arbitrary software, which can include operating systems andapplications. The consumer does not manage or control the underlyingcloud infrastructure but has control over operating systems, storage,deployed applications, and possibly limited control of select networkingcomponents (e.g., host firewalls).

Deployment Models are as follows:

Private cloud: the cloud infrastructure is operated solely for anorganization. It may be managed by the organization or a third party andmay exist on-premises or off-premises.

Community cloud: the cloud infrastructure is shared by severalorganizations and supports a specific community that has shared concerns(e.g., mission, security requirements, policy, and complianceconsiderations). It may be managed by the organizations or a third partyand may exist on-premises or off-premises.

Public cloud: the cloud infrastructure is made available to the generalpublic or a large industry group and is owned by an organization sellingcloud services.

Hybrid cloud: the cloud infrastructure is a composition of two or moreclouds (private, community, or public) that remain unique entities butare bound together by standardized or proprietary technology thatenables data and application portability (e.g., cloud bursting forload-balancing between clouds).

A cloud computing environment is service oriented with a focus onstatelessness, low coupling, modularity, and semantic interoperability.At the heart of cloud computing is an infrastructure that includes anetwork of interconnected nodes.

Referring now to FIG. 1, illustrative cloud computing environment 50 isdepicted. As shown, cloud computing environment 50 includes one or morecloud computing nodes 10 with which local computing devices used bycloud consumers, such as, for example, personal digital assistant (PDA)or cellular telephone 54A, desktop computer 54B, laptop computer 54C,and/or automobile computer system 54N may communicate. Nodes 10 maycommunicate with one another. They may be grouped (not shown) physicallyor virtually, in one or more networks, such as Private, Community,Public, or Hybrid clouds as described hereinabove, or a combinationthereof. This allows cloud computing environment 50 to offerinfrastructure, platforms and/or software as services for which a cloudconsumer does not need to maintain resources on a local computingdevice. It is understood that the types of computing devices 54A-N shownin FIG. 1 are intended to be illustrative only and that computing nodes10 and cloud computing environment 50 can communicate with any type ofcomputerized device over any type of network and/or network addressableconnection (e.g., using a web browser).

Referring now to FIG. 2, a set of functional abstraction layers providedby cloud computing environment 50 (FIG. 1) is shown. It should beunderstood in advance that the components, layers, and functions shownin FIG. 2 are intended to be illustrative only and embodiments of theinvention are not limited thereto. As depicted, the following layers andcorresponding functions are provided:

Hardware and software layer 60 includes hardware and softwarecomponents. Examples of hardware components include: mainframes 61; RISC(Reduced Instruction Set Computer) architecture based servers 62;servers 63; blade servers 64; storage devices 65; and networks andnetworking components 66. In some embodiments, software componentsinclude network application server software 67 and database software 68.

Virtualization layer 70 provides an abstraction layer from which thefollowing examples of virtual entities may be provided: virtual servers71; virtual storage 72; virtual networks 73, including virtual privatenetworks; virtual applications and operating systems 74; and virtualclients 75.

In one example, management layer 80 may provide the functions describedbelow. Resource provisioning 81 provides dynamic procurement ofcomputing resources and other resources that are utilized to performtasks within the cloud computing environment. Metering and Pricing 82provide cost tracking as resources are utilized within the cloudcomputing environment, and billing or invoicing for consumption of theseresources. In one example, these resources may include applicationsoftware licenses. Security provides identity verification for cloudconsumers and tasks, as well as protection for data and other resources.User portal 83 provides access to the cloud computing environment forconsumers and system administrators. Service level management 84provides cloud computing resource allocation and management such thatrequired service levels are met. Service Level Agreement (SLA) planningand fulfillment 85 provide pre-arrangement for, and procurement of,cloud computing resources for which a future requirement is anticipatedin accordance with an SLA.

Workloads layer 90 provides examples of functionality for which thecloud computing environment may be utilized. Examples of workloads andfunctions which may be provided from this layer include: mapping andnavigation 91; software development and lifecycle management 92; virtualclassroom education delivery 93; data analytics processing 94;transaction processing 95; and co-location service 96.

FIG. 3 is a functional block diagram illustrating a distributed dataprocessing environment, generally designated 300, in accordance with oneembodiment of the present invention. The term “distributed” as used inthis specification describes a computer system that includes multiple,physically distinct devices that operate together as a single computersystem. FIG. 3 provides only an illustration of one implementation anddoes not imply any limitations with regard to the environments in whichdifferent embodiments may be implemented. Many modifications to thedepicted environment may be made by those skilled in the art withoutdeparting from the scope of the invention as recited by the claims.

Distributed data processing environment 300 includes host computer 304and host computer 308, all interconnected over network 302.

In general, network 302 can be any combination of connections andprotocols that will support communications between host computer 304 andhost computer 308, and other computing devices (not shown) withindistributed data processing environment 300. Network 302 can be, forexample, a telecommunications network, a local area network (LAN), awide area network (WAN), such as the Internet, or a combination of thethree, and can include wired, wireless, or fiber optic connections.Network 302 can include one or more wired and/or wireless networks thatcan receive and transmit data, voice, and/or video signals, includingmultimedia signals that include voice, data, and video information.

Host computer 304 can be a standalone computing device, a managementserver, a content service, a mobile computing device, or any otherelectronic device or computing system capable of receiving, sending, andprocessing data. In other embodiments, host computer 304 can represent aserver computing system utilizing multiple computers as a server system,such as in a cloud computing environment. In another embodiment, hostcomputer 304 can be a laptop computer, a tablet computer, a netbookcomputer, a personal computer (PC), a desktop computer, a personaldigital assistant (PDA), a smart phone, or any other programmableelectronic device capable of communicating with host computer 308, andother computing devices (not shown) within distributed data processingenvironment 100 via network 302. In another embodiment, host computer304 represents a computing system utilizing clustered computers andcomponents (e.g., database server computers, application servercomputers, etc.) that act as a single pool of seamless resources whenaccessed within distributed data processing environment 100. Hostcomputer 308 may be an equivalent electronic device or computing systemcapable of receiving, sending, and processing data as described withrespect to host computer 304. Host computer 304 may include internal andexternal hardware components, as depicted and described in furtherdetail with respect to FIG. 7.

Host computer 304 includes container 304A and container 304B. Hostcomputer 308 includes container 308A. Container 304A includes aninstance of co-location program 306A, container 304B includes aninstance of co-location program 306B, and container 308A includes aninstance of co-location program 306C.

In some embodiments of the present invention, co-location program 306Asends a bit string s to one or more containers running an instance ofco-location program, such as co-location program 306B and co-locationprogram 306C, by encoding a shared key K using an error correction code(ECC) and successively transferring each bit b in bit string s via oneor more side channels c. Co-location program 306A may iterate over eachbit b of bit string s and send each bit b over the side channels c asfollows: (i) if the bit b=1, co-location program 306A sends the bit b bygenerating a high load on the one or more side channels c for a timeperiod t; and (ii) if the bit b=0, co-location program 306A sends thebit b by staying idle on the one or more side channels c for a timeperiod t. In some embodiments, co-location program 306A may continuesending the bit string s repeatedly until a trial period t*Δt haselapsed.

In some embodiments of the present invention, co-location program 306Amay generate the shared key K. In these and other embodiments,co-location program 306A may send the shared key K to one or morecontainers running an instance of co-location program, such asco-location program 306B and co-location program 306C. In someembodiments, one or more containers running an instance of co-locationprogram, including co-location program 306A, may receive the shared keyK as part of their respective container specifications. In otherembodiments, one or more containers running an instance of co-locationprogram, including co-location program 306A, may receive the shared keyK from other computing devices (not shown).

Host computer 304 includes an instance of co-location program 306B. Hostcomputer 308 includes an instance of co-location program 306C. In someembodiments of the present invention, one or more containers running aninstance of co-location program, such as co-location program 306B andco-location program 306C, receive a bit string s′ over the one or moreside channels c within the trial period t*Δt and determine a key K′ bydecoding the bit string s′ using the ECC. In some embodiments, one ormore containers running an instance of co-location program may comparethe shared key K with the respective determined key K′. If the sharedkey K matches the determined key K′, the respective instance ofco-location program determines that it is co-located in the same hostcomputer as co-location program 306A. If the shared key K does not matchthe determined key K′, the respective instance of co-location programdetermines that it is not co-located in the same host computer asco-location program 306A.

Co-location program 306 is depicted and described in further detail withrespect to FIG. 4. Referring to flowchart 400, co-location program 306allows communication between a first application and a secondapplication running on container hosts in a cloud server where the firstapplication and the second application do not have access to hostcommands.

Processing begins at operation 405, where co-location program 306Agenerates a shared key K, including a bit string s, where s is obtainedby encoding the shared key K using an error-correcting code (ECC). Insome embodiments of the present invention, the shared key K is a bitstring of length k<n, where n is the maximum length of the ECC. In someembodiments, the shared key K includes the time period t and a trialperiod t*Δt. In some embodiments, the time period t represents theduration to transmit exactly one bit of the ECC. In some embodiments,the trial period t*Δt represents the duration to transmit the n bits ofthe ECC.

In some embodiments, the shared key K further includes an identificationof one or more side channels c for communication between one or morecontainers running an instance of co-location program, such asco-location program 306B and/or co-location program 306C. In someembodiments of the present invention, the side channel includes anyresource such that, when the first application puts an unusually highload over a time period t, a second application co-located on a samehost can observe its unusual high load. By way of example, co-locationprogram 306A may include the following as a side channel c: (i) theprocessor, by performing intensive operations on a processor for a timeperiod t, (ii) the memory, by utilizing the totality of the allocatedmemory for a time period t; and/or (iii) the disk storage, by storing alarge object and maintaining the object stored.

In an exemplary embodiment, there are three containers (i.e., container304A, container 304B, and container 308A) each running an instance ofco-location program (i.e., co-location program 306A, co-location program306B, and co-location program 306C, respectively). As shown in FIG. 5(see, table 500), co-location program 306A generates the shared keyK=1011. Co-location program 306A also specifies time period t=0.2 s andtrial period t*Δt=1.4 s. Co-location program 306A further specifies sidechannel c=CPU. In this example, co-location program 306A determines theECC by encoding K using a (7,4)-hamming code with corresponding bitstring s=1011100.

Processing continues at operation 410, where co-location program 306Asends the shared key K to one or more containers running an instance ofco-location program, such as co-location program 306B and/or co-locationprogram 306C. In some embodiments of the present invention, co-locationprogram 306A sends the shared key K to one or more containers running aninstance of co-location program via network 302. In other embodiments,one or more containers running an instance of co-location program,including co-location program 306A, may include the shared key K as partof the container specification.

In the exemplary embodiment, co-location program 306A sends the sharedkey K with co-location program 306B and co-location program 306C overnetwork 302 to initiate detection of containers located in the same hostas container 304A.

Processing continues at operation 415, where one or more containersrunning an instance of co-location program, such as co-location program306B and/or co-location program 306C, receive a shared key K fromco-location program 306A. In some embodiments of the present invention,one or more containers running an instance of co-location programreceive a shared key K from co-location program 306A and/or othercomputing devices (not shown) via network 302. In other embodiments, oneor more containers running an instance of co-location program, includingco-location program 306A, may include the shared key K as part of thecontainer specification.

In the exemplary embodiment, co-location program 306B and co-locationprogram 306C receive the shared key K from co-location program 306A overnetwork 302 to initiate detection of containers located in the same hostas container 304A.

Processing continues at operation 420, where co-location program 306Asuccessively transfers each bit b in bit string s over the one or moreside channels c within the trial period t*Δt. In some embodiments of thepresent invention, co-location program 306A iterates over each bit b ofbit string s and sends each bit b by over the side channels c. If thebit b=1, co-location program 306A sends the bit b by generating a highload on the side channel c for a time period t. If the bit b=0,co-location program 306A sends the bit b by staying idle on the sidechannel c for a time period t.

In some embodiments, co-location program 306A may generate a high loadon the memory (e.g., a volatile memory) as a side channel by using ahigh amount (e.g., more than 80%) of the allocated memory of thecontainer. In some embodiments, co-location program 306A may generate ahigh load on the disk storage (e.g., a persistent memory) as a sidechannel c by storing a large object (e.g., more than 10% of the diskstorage available to the container) and maintaining the object storedfor a time period t. In some embodiments, co-location program 306A maygenerate a high load on the CPU as a side channel c by consistentlyproducing a high CPU usage (e.g., more than 90% usage) for a time periodt. In some embodiments, co-location program 306A may generate a low loadon the memory (e.g., a volatile memory) as a side channel by using a lowamount (e.g., less than 5%) of the allocated memory of the container. Insome embodiments, co-location program 306A may generate a low load onthe disk storage (e.g., a persistent memory) as a side channel c byusing a low amount of disk storage (e.g., deleting a large object) for atime period t. In some embodiments, co-location program 306A maygenerate a low load on the CPU as a side channel c by waiting (e.g.,generating no operation calls) for a time period t. In some embodiments,co-location program 306A sends bit string s repeatedly while trialperiod t*Δt has not elapsed.

It should be noted that the above examples of a “high load,” a “highamount,” a “low load,” and a “low amount,” are merely examples, and thatmany other known (or yet to be known) methods and values for determiningand communicating relatively high and relatively low loads and amountsmay be used, so long as the differences between what comprises a “high”load or amount and what comprises a “low” load or amount is understoodby both the sender and the recipient of a given bit string beingdelivered over a side channel. Furthermore, while the above embodimentsgenerally indicate that “high” loads represent a bit value of “1” andthat “low” loads represent a bit value of “0,” these examples also arenot meant to be limiting, and other embodiments may provide the oppositearrangement (“high” loads representing bit values of “0” and “low” loadsrepresenting bit values of “1”) or may provide for bit values beyondthose in a binary, two-state bit configuration (for example, having a“high” load represent a bit value of “0,” a “medium” load represent abit value of “1,” and a “low” load represent a bit value of “2”).

In the exemplary embodiment, co-location program 306A successively sendseach bit in bit string s=1011100 over the side channel c correspondingto the CPU. As shown in FIG. 6 (see, graph 600), this objective isachieved by iterating over each bit b in bit string s. If bit b=1,co-location program 306A generates a consistently high CPU usage fort=0.2 s. Conversely, if bit b=0, co-location program 306A pausesexecution (e.g., by using sleep or a similar system call) for t=0.2 s.In this example, trial period t*Δt=1.4 s elapses after sending bitstring s once.

Processing proceeds at operation 425, where one or more containersrunning an instance of co-location program, such as co-location program306B and/or co-location program 306C, receive a bit string s′ over theone or more side channels c within the trial period t*Δt and determine akey K′ by decoding the bit string s′ using the ECC. In some embodimentsof the present invention, one or more containers running an instance ofco-location program receive the bit string s′ by observing high loads onthe one or more side channels c consistent with the time period t andthe trial period t*Δt.

In the exemplary embodiment, co-location program 306B receives bitstring s′=1011100 the side channel corresponding to the CPU by observingthe CPU usage behavior of co-location program 306A. Co-location program306B decodes s′=1011100 to K′=1011 by using a (7,4)-hamming code. On theother hand, co-location program 306C receives bit string s′=0000000 theside channel corresponding to the CPU because it cannot observe anypattern of CPU usage behavior. Co-location program 306C decodess′=0000000 to K′=0000 by using a (7,4)-hamming code.

Processing proceeds at operation 430, where one or more containersrunning an instance of co-location program, such as co-location program306B and/or co-location program 306C, compare the shared key K withtheir respective determined key K′. In some embodiments of the presentinvention, one or more containers running an instance of co-locationprogram compare the shared key K with their respective determined key K′by direct comparison of the respective values of K and K′. In otherembodiments, the comparison may be achieved by other methods such asdetermining that the result of a bitwise exclusive-or is zero.

In the exemplary embodiment, co-location program 306B compares K=1011with determined K′=1011. Co-location program 306C compares K=1011 withdetermined K′=0000.

If the shared key K does not match the determined key K′ (operation 435,“no” branch), processing continues at operation 440, where one or morecontainers running an instance of co-location program, such asco-location program 306B and/or co-location program 306C, determine thatco-location program 306A is not co-located on the same host.

In the exemplary embodiment, co-location program 306C determines thatshared key K=0000 is not equal to determined key K′=1011. Therefore,co-location program 306C determines that container 304C is not hosted inthe same host computer as container 304A.

If the shared key K matches the determined key K′ (operation 435, “yes”branch), processing continues at operation 445, where one or morecontainers running an instance of co-location program, such asco-location program 306B and/or co-location program 306C, determine thatco-location program 306A is co-located on the same host.

In the exemplary embodiment, co-location program 306B determines thatshared key K=1011 is equal to determined key K′=1011. Therefore,co-location program 306B determines that container 304B is hosted in thesame host computer as container 304A.

FIG. 7 depicts a block diagram 700 of components of host computer 304within distributed data processing environment 300 of FIG. 3, inaccordance with an embodiment of the present invention. It should beappreciated that FIG. 7 provides only an illustration of oneimplementation and does not imply any limitations with regard to theenvironments in which different embodiments can be implemented. Manymodifications to the depicted environment can be made.

The programs described herein are identified based upon the applicationfor which they are implemented in a specific embodiment of theinvention. However, it should be appreciated that any particular programnomenclature herein is used merely for convenience, and thus theinvention should not be limited to use solely in any specificapplication identified and/or implied by such nomenclature.

Computing device 705 and host computer 304 include communications fabric702, which provides communications between computer processor(s) 704,memory 706, persistent storage 708, communications unit 710, andinput/output (I/O) interface(s) 712.

Communications fabric 702 can be implemented with any architecturedesigned for passing data and/or control information between processors(such as microprocessors, communications and network processors, etc.),system memory, peripheral devices, and any other hardware componentswithin a system. For example, communications fabric 702 can beimplemented with one or more buses.

Memory 706 and persistent storage 708 are computer-readable storagemedia. In this embodiment, memory 706 includes random access memory(RAM) 714 and cache memory 716. In general, memory 706 can include anysuitable volatile or non-volatile computer-readable storage media.

Co-location program 306 is stored in persistent storage 708 forexecution by one or more of the respective computer processors 704 viaone or more memories of memory 706. In this embodiment, persistentstorage 708 includes a magnetic hard disk drive. Alternatively, or inaddition to a magnetic hard disk drive, persistent storage 708 caninclude a solid state hard drive, a semiconductor storage device,read-only memory (ROM), erasable programmable read-only memory (EPROM),flash memory, or any other computer-readable storage media that iscapable of storing program instructions or digital information.

The media used by persistent storage 708 may also be removable. Forexample, a removable hard drive may be used for persistent storage 708.Other examples include optical and magnetic disks, thumb drives, andsmart cards that are inserted into a drive for transfer onto anothercomputer-readable storage medium that is also part of persistent storage708.

Communications unit 710, in these examples, provides for communicationswith other data processing systems or devices, including resources ofdistributed data processing environment 100. In these examples,communications unit 710 includes one or more network interface cards.Communications unit 710 may provide communications through the use ofeither or both physical and wireless communications links. Co-locationprogram 306 may be downloaded to persistent storage 708 throughcommunications unit 710.

I/O interface(s) 712 allows for input and output of data with otherdevices that may be accessible to computing device 705 and host computer304, such as host computer 308, and other computing devices (not shown).For example, I/O interface 712 may provide a connection to externaldevices 718 such as a keyboard, keypad, a touch screen, and/or someother suitable input device. External devices 718 can also includeportable computer-readable storage media such as, for example, thumbdrives, portable optical or magnetic disks, and memory cards. Softwareand data used to practice embodiments of the present invention, e.g.,co-location program 306 can be stored on such portable computer-readablestorage media and can be loaded onto persistent storage 708 via I/Ointerface(s) 712. I/O interface(s) 712 also connect to a display 720.

Display 720 provides a mechanism to display data to a user and may be,for example, a computer monitor.

The programs described herein are identified based upon the applicationfor which they are implemented in a specific embodiment of theinvention. However, it should be appreciated that any particular programnomenclature herein is used merely for convenience, and thus theinvention should not be limited to use solely in any specificapplication identified and/or implied by such nomenclature.

The present invention may be a system, a method, and/or a computerprogram product. The computer program product may include a computerreadable storage medium (or media) having computer readable programinstructions thereon for causing a processor to carry out aspects of thepresent invention.

The computer readable storage medium can be any tangible device that canretain and store instructions for use by an instruction executiondevice. The computer readable storage medium may be, for example, but isnot limited to, an electronic storage device, a magnetic storage device,an optical storage device, an electromagnetic storage device, asemiconductor storage device, or any suitable combination of theforegoing. A non-exhaustive list of more specific examples of thecomputer readable storage medium includes the following: a portablecomputer diskette, a hard disk, a random access memory (RAM), aread-only memory (ROM), an erasable programmable read-only memory (EPROMor Flash memory), a static random access memory (SRAM), a portablecompact disc read-only memory (CD-ROM), a digital versatile disk (DVD),a memory stick, a floppy disk, a mechanically encoded device such aspunch-cards or raised structures in a groove having instructionsrecorded thereon, and any suitable combination of the foregoing. Acomputer readable storage medium, as used herein, is not to be construedas being transitory signals per se, such as radio waves or other freelypropagating electromagnetic waves, electromagnetic waves propagatingthrough a waveguide or other transmission media (e.g., light pulsespassing through a fiber-optic cable), or electrical signals transmittedthrough a wire.

Computer readable program instructions described herein can bedownloaded to respective computing/processing devices from a computerreadable storage medium or to an external computer or external storagedevice via a network, for example, the Internet, a local area network, awide area network and/or a wireless network. The network may comprisecopper transmission cables, optical transmission fibers, wirelesstransmission, routers, firewalls, switches, gateway computers and/oredge servers. A network adapter card or network interface in eachcomputing/processing device receives computer readable programinstructions from the network and forwards the computer readable programinstructions for storage in a computer readable storage medium withinthe respective computing/processing device.

Computer readable program instructions for carrying out operations ofthe present invention may be assembler instructions,instruction-set-architecture (ISA) instructions, machine instructions,machine dependent instructions, microcode, firmware instructions,state-setting data, or either source code or object code written in anycombination of one or more programming languages, including an objectoriented programming language such as Smalltalk, C++ or the like, andconventional procedural programming languages, such as the “C”programming language or similar programming languages. The computerreadable program instructions may execute entirely on the user'scomputer, partly on the user's computer, as a stand-alone softwarepackage, partly on the user's computer and partly on a remote computeror entirely on the remote computer or server. In the latter scenario,the remote computer may be connected to the user's computer through anytype of network, including a local area network (LAN) or a wide areanetwork (WAN), or the connection may be made to an external computer(for example, through the Internet using an Internet Service Provider).In some embodiments, electronic circuitry including, for example,programmable logic circuitry, field-programmable gate arrays (FPGA), orprogrammable logic arrays (PLA) may execute the computer readableprogram instructions by utilizing state information of the computerreadable program instructions to personalize the electronic circuitry,in order to perform aspects of the present invention.

Aspects of the present invention are described herein with reference toflowchart illustrations and/or block diagrams of methods, apparatus(systems), and computer program products according to embodiments of theinvention. It will be understood that each block of the flowchartillustrations and/or block diagrams, and combinations of blocks in theflowchart illustrations and/or block diagrams, can be implemented bycomputer readable program instructions.

These computer readable program instructions may be provided to aprocessor of a general-purpose computer, a special purpose computer, orother programmable data processing apparatus to produce a machine, suchthat the instructions, which execute via the processor of the computeror other programmable data processing apparatus, create means forimplementing the functions/acts specified in the flowchart and/or blockdiagram block or blocks. These computer readable program instructionsmay also be stored in a computer readable storage medium that can directa computer, a programmable data processing apparatus, and/or otherdevices to function in a particular manner, such that the computerreadable storage medium having instructions stored therein comprises anarticle of manufacture including instructions which implement aspects ofthe function/act specified in the flowchart and/or block diagram blockor blocks.

The computer readable program instructions may also be loaded onto acomputer, other programmable data processing apparatus, or other deviceto cause a series of operational steps to be performed on the computer,other programmable apparatus or other device to produce a computerimplemented process, such that the instructions which execute on thecomputer, other programmable apparatus, or other device implement thefunctions/acts specified in the flowchart and/or block diagram block orblocks.

The flowchart and block diagrams in the Figures illustrate thearchitecture, functionality, and operation of possible implementationsof systems, methods, and computer program products according to variousembodiments of the present invention. In this regard, each block in theflowchart or block diagrams may represent a module, a segment, or aportion of instructions, which comprises one or more executableinstructions for implementing the specified logical function(s). In somealternative implementations, the functions noted in the blocks may occurout of the order noted in the Figures. For example, two blocks shown insuccession may, in fact, be executed substantially concurrently, or theblocks may sometimes be executed in the reverse order, depending uponthe functionality involved. It will also be noted that each block of theblock diagrams and/or flowchart illustration, and combinations of blocksin the block diagrams and/or flowchart illustration, can be implementedby special purpose hardware-based systems that perform the specifiedfunctions or acts or carry out combinations of special purpose hardwareand computer instructions.

The descriptions of the various embodiments of the present inventionhave been presented for purposes of illustration, but are not intendedto be exhaustive or limited to the embodiments disclosed. Manymodifications and variations will be apparent to those of ordinary skillin the art without departing from the scope and spirit of the invention.The terminology used herein was chosen to best explain the principles ofthe embodiment, the practical application or technical improvement overtechnologies found in the marketplace, or to enable others of ordinaryskill in the art to understand the embodiments disclosed herein.

What is claimed is:
 1. A method, comprising: receiving, by a firstprogram in a first cloud container on a first host, a bit string over aside channel within a trial period of time, wherein the side channelincludes a first resource on the first host that is accessible by cloudcontainers located on the first host, and wherein the bit string isreceived by monitoring the first resource for activity indicative of bitvalues; determining, by the first program, whether a key correspondingto the bit string matches a pre-determined key corresponding to a secondprogram in a second cloud container; and determining, by the firstprogram, whether the second cloud container is located on the first hostbased, at least in part, on whether the key corresponding to the bitstring matches the pre-determined key.
 2. The method of claim 1, whereindetermining whether the shared key matches a pre-determined keycomprises: determining, by the first program, the key corresponding tothe bit string by decoding the bit string using a predetermined errorcorrecting code; and determining, by the first program, whether the keycorresponding to the bit string matches the pre-determined key.
 3. Themethod of claim 1, further comprising receiving, by the first program, ashared key from the second program in the second cloud container,wherein the shared key is the pre-determined key.
 4. The method of claim1, further comprising receiving, by the first program, a shared key aspart of a container specification file, wherein the shared key is thepre-determined key.
 5. The method of claim 1, wherein a high load on thefirst resource for a fixed period of time is indicative of a bit valueequal of one and wherein a low load on the first resource for a fixedperiod of time is indicative of a bit value equal of zero.
 6. The methodof claim 5, wherein the first resource includes a processor, wherein ahigh load on the first resource includes performing processor-intensiveoperations on the processor for the fixed period of time, and wherein alow load on the first resource includes performing a low amount ofoperation calls on the processor for the fixed period of time.
 7. Themethod of claim 5, wherein the first resource includes a volatilememory, wherein a high load on the first resource includes utilizing ahigh amount of the allocated memory for the fixed period of time, andwherein a low load on the first resource includes utilizing a low amountof allocated memory for the fixed period of time.
 8. The method of claim5, wherein the first resource includes a non-volatile memory, wherein ahigh load on the first resource includes utilizing a high amount ofstorage storing a large object in the non-volatile memory for the fixedperiod of time, and wherein a low load on the first resource includesutilizing a low amount of storage for the fixed period of time.
 9. Acomputer program product, comprising: one or more computer readablestorage devices and program instructions stored on the one or morecomputer readable storage devices, the stored program instructionscomprising: program instructions to receive a bit string over a sidechannel within a trial period of time, wherein the side channel includesa first resource on the first host that is accessible by cloudcontainers located on the first host, and wherein the bit string isreceived by monitoring the first resource for activity indicative of bitvalues; program instructions to determine whether a key corresponding tothe bit string matches a pre-determined key corresponding to a secondprogram in a second cloud container; and program instructions todetermine whether the second cloud container is located on the firsthost based, at least in part, on whether the key corresponding to thebit string matches the pre-determined key.
 10. The computer programproduct of claim 9, wherein the program instructions to determiningwhether the shared key matches a pre-determined key comprises: programinstructions to determine the key corresponding to the bit string bydecoding the bit string using a predetermined error correcting code; andprogram instructions to determine whether the key corresponding to thebit string matches the pre-determined key.
 11. The computer programproduct of claim 9, wherein a high load on the first resource for afixed period of time is indicative of a bit value equal of one andwherein a low load on the first resource for a fixed period of time isindicative of a bit value equal of zero.
 12. The computer programproduct of claim 11, wherein the first resource includes a processor,wherein a high load on the first resource includes performingprocessor-intensive operations on the processor for the fixed period oftime, and wherein a low load on the first resource includes performing alow amount of operation calls on the processor for the fixed period oftime.
 13. The computer program product of claim 11, wherein the firstresource includes a volatile memory, wherein a high load on the firstresource includes utilizing a high amount of the allocated memory forthe fixed period of time, and wherein a low load on the first resourceincludes utilizing a low amount of allocated memory for the fixed periodof time.
 14. The computer program product of claim 11, wherein the firstresource includes a non-volatile memory, wherein a high load on thefirst resource includes utilizing a high amount of storage storing alarge object in the non-volatile memory for the fixed period of time,and wherein a low load on the first resource includes utilizing a lowamount of storage for the fixed period of time.
 15. A computer system,comprising: one or more computer processors; one or more computerreadable storage devices; program instructions stored on the one or morecomputer readable storage devices for execution by at least one of theone or more computer processors, the stored program instructionscomprising: program instructions to receive a bit string over a sidechannel within a trial period of time, wherein the side channel includesa first resource on the first host that is accessible by cloudcontainers located on the first host, and wherein the bit string isreceived by monitoring the first resource for activity indicative of bitvalues; program instructions to determine whether a key corresponding tothe bit string matches a pre-determined key corresponding to a secondprogram in a second cloud container; and program instructions todetermine whether the second cloud container is located on the firsthost based, at least in part, on whether the key corresponding to thebit string matches the pre-determined key.
 16. The computer system ofclaim 15, wherein the program instructions to determining whether theshared key matches a pre-determined key comprises: program instructionsto determine the key corresponding to the bit string by decoding the bitstring using a predetermined error correcting code; and programinstructions to determine whether the key corresponding to the bitstring matches the pre-determined key.
 17. The computer system of claim15, wherein a high load on the first resource for a fixed period of timeis indicative of a bit value equal of one and wherein a low load on thefirst resource for a fixed period of time is indicative of a bit valueequal of zero.
 18. The computer system of claim 17, wherein the firstresource includes a processor, wherein a high load on the first resourceincludes performing processor-intensive operations on the processor forthe fixed period of time, and wherein a low load on the first resourceincludes performing a low amount of operation calls on the processor forthe fixed period of time.
 19. The computer system of claim 17, whereinthe first resource includes a volatile memory, wherein a high load onthe first resource includes utilizing a high amount of the allocatedmemory for the fixed period of time, and wherein a low load on the firstresource includes utilizing a low amount of allocated memory for thefixed period of time.
 20. The computer system of claim 17, wherein thefirst resource includes a non-volatile memory, wherein a high load onthe first resource includes utilizing a high amount of storage storing alarge object in the non-volatile memory for the fixed period of time,and wherein a low load on the first resource includes utilizing a lowamount of storage for the fixed period of time.